The present invention provides an optical recording medium which is inhibited or prevented from sticking of lubricants onto a light emitting face of a solid immersion lens. The optical recording medium 10 of the present invention comprises a substrate 1 and, provided thereon in succession, a reflective layer 2, a recording layer 4, a protective layer 6 and a lubricating layer 7. The lubricating layer 7 is heated and/or irradiated with ultraviolet rays to adjust the lubricant bonding rate to at least 60%, thereby to reduce the amount of physical adsorptive lubricant contained in the lubricating layer 7. As a result, when recording and reproduction are carried out using a floating type optical head provided with a solid immersion lens, the lubricant hardly sticks to the light emitting face of the solid immersion lens. The lubricant bonding rate can be enhanced to 80% or more by rinsing the lubricating layer with a solvent after the heating and/or the irradiation with ultraviolet rays.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An optical recording medium comprising a substrate and, provided thereon in succession, a reflective layer, a recording layer, a protective layer and a lubricating layer comprising a lubricant, where a lubricant bonding rate of the lubricant to the protective layer is 60-100%; wherein the optical recording medium is irradiated with light from the side of the lubricating layer by a floating type optical head to carry out at least one of recording and reproduction, and wherein the lubricant is a perfluoro polyether having at least one functional group selected from the group consisting of an alcohol group, a carboxyl group, an ester group and a piperonyl group at one or both ends of the molecule and having a molecular weight of 2000-10000.
2. An optical recording medium according to claim 1 , wherein the protective layer comprises carbon.
3. An optical recording medium according to claim 2 , wherein the carbon contains at least one element selected from the group consisting of hydrogen, nitrogen, silicon and fluorine.
4. An optical recording medium according to claim 3 , wherein the lubricant bonding rate is 80-100%.
5. An optical recording medium according to claim 1 , which is a magneto-optical recording medium.
6. An optical recording medium according to claim 1 , wherein the floating type optical head is provided with a solid immersion lens.
7. An optical recording medium according to claim 6 , wherein the floating type optical head is further provided with a magnetic coil for applying a magnetic field to the optical recording medium.
8. An optical recording medium according to claim 1 , wherein the lubricant is a perfluoro polyether in which at least one end group of the molecule has two or more hydroxyl groups.
9. An optical recording medium according to claim 8 , wherein the lubricant has a molecular weight of 2000-10000.
10. An optical recording medium according to claim 9 , wherein the lubricant is a perfluoro polyether represented by HO CH 2 CH(OH)CH 2 OCH 2 CF 2 O (C 2 F 4 O) n (CF 2 O) m CF 2 CH 2 OCH 2 CH(OH)CH 2 OH.
11. An optical recording medium comprising a substrate and, provided thereon in succession, a reflective layer, a recording layer, a protective layer and a lubricating layer comprising a lubricant, where the lubricant is a perfluoro polyether in which at least one end group of the molecule has two or more hydroxyl groups.
12. An optical recording medium according to claim 11 , wherein the lubricant has a molecular weight of 2000-10000.
13. An optical recording medium according to claim 12 , wherein the lubricant is a perfluoro polyether represented by HO CH 2 CH(OH)CH 2 OCH 2 CF 2 O (C 2 F 4 O) n (CF 2 O) m CF 2 CH 2 OCH 2 CH (OH) CH 2 OH.
14. An optical recording medium according to claim 11 , wherein the lubricant bonding rate of the lubricant to the protective layer is 60-100%.
15. An optical recording medium according to claim 14 , wherein the protective layer comprises carbon.
16. An optical recording medium according to claim 15 , wherein the carbon protective layer contains at least one element selected from the group consisting of hydrogen, nitrogen, silicon and fluorine.
17. An optical recording medium according to claim 11 , which is irradiated with light from the side of the lubricating layer by a floating type optical head to carry out at least one of recording and reproduction.
18. An optical recording medium according to claim 17 , wherein the floating type optical head is provided with a solid immersion lens.
19. An optical recording medium according to claim 18 , wherein the floating type optical head is further provided with a magnetic coil for applying a magnetic field to the optical recording medium.
20. An optical recording medium according to claim 19 , wherein the lubricant bonding rate of the lubricant to the protective layer is 60-80%.
21. An optical recording medium according to claim 11 , which is a magneto-optical recording medium.
22. A process for producing an optical recording medium comprising a substrate and, provided thereon in succession, a reflective layer, a recording layer, a protective layer and a lubricating layer, which comprises coating a lubricant on the protective layer and thereafter subjecting the lubricant to at least one of heating or irradiation with ultraviolet ray so that the lubricant bonding rate of the lubricant to the protective layer is in the range of 60-100%.
23. A process according to claim 21 , wherein the lubricant is a perfluoro polyether in which at least one end group of the molecule has two or more hydroxyl groups.
24. A process according to claim 23 , wherein the lubricant has a molecular weight of 2000-10000.
25. A process according to claim 24 , wherein the lubricant is a perfluoro polyether represented by HO CH 2 CH(OH)CH 2 OCH 2 CF 2 O (C 2 F 4 O) n (CF 2 O) m CF 2 CH 2 OCH 2 CH(OH)CH 2 OH.
26. A process according to claim 23 , wherein the temperature for the heating is in the range of 50-120 C.
27. A process according to claim 23 , wherein the ultraviolet ray used for the irradiation has a wavelength of 185-254 nm.
28. A process according to claim 22 , which additionally comprises rinsing the lubricating layer with a solvent after carrying out at least one of the heating and the irradiation with ultraviolet rays.
29. A process according to claim 28 , wherein the solvent is at least one solvent selected from the group consisting of perfluorooctane, perfluorohexane, C 4 F 9 OCH 3 , C 4 F 9 OC 2 H 5 and GARDEN.
30. A process according to claim 27 , wherein the irradiation with ultraviolet rays is carried out in an inert atmosphere.
31. A process according to claim 30 , wherein the inert atmosphere is an atmosphere selected from the group consisting of nitrogen atmosphere, argon atmosphere and helium atmosphere.
32. A process according to claim 22 , wherein the optical recording medium is a magneto-optical recording medium.
33. A process according to claim 22 , wherein the resulting optical recording medium is irradiated with light from the side of the lubricating layer by a floating type optical head to carry out at least one of recording and reproduction.
34. A process according to claim 33 , wherein the floating type optical head is provided with a solid immersion lens.
35. A process according to claim 34 , wherein the floating type optical head is further provided with a magnetic coil for applying a magnetic field to the optical recording medium.
36. An optical recording medium produced by the process of claim 22 .
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 11, 1999
February 12, 2002
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